delayed data fetching in RocksDB ( Java ) as queue

I am using RocksDB as the queue for my application. The logic is based on the incremental numbers as keys in a single column family. The insert rate is 5000 inserts per minute. The data is fetched from RocksDB using RocksIterator. There is delete after every data processing. The setup is put under load test, Initially, the fetching speed was very high ( 1 ms ). After 10 days the inserts are stopped as already large junk of data (12G is accumulated in RocksDB ) and again the fetching speed is good for a week and after that, the data fetching time increases ( 700 ms). I know the reason for the increase is due to continuous deletes. Is there any way to optimize RocksDB for queuing as it involves continuous inserts, reads and deletes.

Options file

# RocksDB option file.

[Version]
rocksdb_version=6.0.1
options_file_version=1.1

[DBOptions]
preserve_deletes=false
allow_ingest_behind=false
dump_malloc_stats=false
info_log_level=INFO_LEVEL
write_thread_max_yield_usec=100
avoid_flush_during_shutdown=false
enable_write_thread_adaptive_yield=true
wal_recovery_mode=kPointInTimeRecovery
fail_if_options_file_error=false
stats_history_buffer_size=1048576
stats_persist_period_sec=600
delete_obsolete_files_period_micros=21600000000
bytes_per_sync=0
enable_pipelined_write=false
max_subcompactions=1
db_log_dir=
wal_dir=/home/test/Queue-Scalability/Jun-29/PersistentCache/RocksDB/data
max_log_file_size=0
manifest_preallocation_size=4194304
delayed_write_rate=16777216
log_file_time_to_roll=0
avoid_flush_during_recovery=false
write_thread_slow_yield_usec=3
keep_log_file_num=5
table_cache_numshardbits=6
max_file_opening_threads=16
max_background_flushes=-1
base_background_compactions=-1
max_background_compactions=-1
use_fsync=false
use_adaptive_mutex=false
wal_bytes_per_sync=0
random_access_max_buffer_size=1048576
atomic_flush=false
compaction_readahead_size=0
manual_wal_flush=false
new_table_reader_for_compaction_inputs=false
max_total_wal_size=0
skip_stats_update_on_db_open=false
skip_log_error_on_recovery=false
max_manifest_file_size=1073741824
paranoid_checks=true
stats_dump_period_sec=600
recycle_log_file_num=0
is_fd_close_on_exec=true
error_if_exists=false
enable_thread_tracking=false
create_missing_column_families=false
WAL_ttl_seconds=0
create_if_missing=true
access_hint_on_compaction_start=NORMAL
max_background_jobs=2
allow_2pc=false
use_direct_io_for_flush_and_compaction=false
db_write_buffer_size=104857600
two_write_queues=false
use_direct_reads=false
allow_concurrent_memtable_write=true
allow_mmap_writes=false
writable_file_max_buffer_size=1048576
WAL_size_limit_MB=0
allow_fallocate=true
max_open_files=100
allow_mmap_reads=false
advise_random_on_open=true

[CFOptions "M2MDataProcessorKeyVsDeviceIdentifier"]
compaction_pri=kMinOverlappingRatio
merge_operator=nullptr
compaction_filter_factory=nullptr
memtable_factory=SkipListFactory
memtable_insert_with_hint_prefix_extractor=nullptr
comparator=leveldb.BytewiseComparator
target_file_size_base=67108864
max_sequential_skip_in_iterations=8
compaction_style=kCompactionStyleLevel
max_bytes_for_level_base=268435456
bloom_locality=0
write_buffer_size=67108864
compression_per_level=
memtable_huge_page_size=0
max_successive_merges=0
arena_block_size=8388608
memtable_whole_key_filtering=false
target_file_size_multiplier=1
max_bytes_for_level_multiplier_additional=1:1:1:1:1:1:1
num_levels=7
min_write_buffer_number_to_merge=1
max_write_buffer_number_to_maintain=0
max_write_buffer_number=2
compression=kSnappyCompression
level0_stop_writes_trigger=36
level0_slowdown_writes_trigger=20
compaction_filter=nullptr
level0_file_num_compaction_trigger=1
max_compaction_bytes=1677721600
compaction_options_universal={allow_trivial_move=false;stop_style=kCompactionStopStyleTotalSize;compression_size_percent=-1;max_size_amplification_percent=200;max_merge_width=4294967295;min_merge_width=2;size_ratio=1;}
memtable_prefix_bloom_size_ratio=0.000000
hard_pending_compaction_bytes_limit=274877906944
ttl=0
table_factory=BlockBasedTable
soft_pending_compaction_bytes_limit=68719476736
prefix_extractor=nullptr
bottommost_compression=kDisableCompressionOption
force_consistency_checks=false
paranoid_file_checks=false
compaction_options_fifo={allow_compaction=false;max_table_files_size=1073741824;}
max_bytes_for_level_multiplier=10.000000
optimize_filters_for_hits=false
level_compaction_dynamic_level_bytes=false
inplace_update_num_locks=10000
inplace_update_support=false
disable_auto_compactions=false
report_bg_io_stats=false